Heat Capacity of K3Fe(CN)6 and CuK2(SO4)2·6H2O below 1 °K

Abstract
Measurements of the heat capacity of potassium ferricyanide for 0.075T0.5°K and of copper potassium Tutton salt for 0.021T0.28°K are presented. A structured heat-capacity peak was found for the ferricyanide around 0.130°K. A λ-type heat-capacity peak was found for the Tutton salt, with Tλ0.0295°K. Entropy calculations, a discussion of the results, and a comparison with previous data are also presented.